DTMB-based carrier mode detection system and receiving system having the same

1. A Digital Terrestrial Multimedia Broadcasting (DTMB)-based carrier mode detection system, comprising: a first Transmission Parameter Signaling (TPS) decoder, for receiving M frequency domain input signals to produce M first mask signals, and performing an absolute operation on the M first mask signals to select a maximum result as a first absolute maximum mask signal for output, where M is a positive integer; a first carrier mode calculator, for receiving N frequency domain input signals to calculate a sum of the N frequency domain input signals and produce a first summation carrier signal, and performing the absolute operation on the first summation carrier signal to produce a first absolute summation carrier signal, where N is a positive integer; a second TPS decoder, for receiving M time domain input signals to produce M second mask signals, and performing the absolute operation on the M second mask signals to select a maximum result as a second absolute maximum mask signal for output; a second carrier mode calculator for receiving N time domain input signals to calculate a sum of the N time domain input signals and produce a second summation carrier signal, and performing the absolute operation on the second summation carrier signal to produce a second absolute summation carrier signal; and a determinator, connected to the first TPS decoder, the first carrier calculator, the second TPS decoder and the second carrier calculator, for determining a carrier mode to be multi-carrier mode or single-carrier mode based on the first absolute maximum mask signal, the first absolute summation carrier signal, the second absolute maximum mask signal and the second absolute summation carrier signal.

2. The detection system as claimed in claim 1 , wherein the determinator comprises: a first adder, for receiving the first absolute maximum mask signal and the first absolute summation carrier signal to produce a first addition signal; a second adder, for receiving the second absolute maximum mask signal and the second absolute summation carrier signal to produce a second addition signal; an adjustor, connected to the second adder, for adjusting the second addition signal to produce an adjustment addition signal; a third adder, connected to the first adder and the adjuster for adding the first addition signal and the adjustment addition signal to produce a third addition signal; and a first sign judger, connected to the third adder, for outputting a first sign signal based on the third addition signal to thereby judge the carrier mode to be the multi-carrier mode or the single-carrier mode.

3. The detection system as claimed in claim 2 , wherein the carrier mode is the single-carrier mode when the first sign signal is a positive sign, otherwise the carrier mode is the multi-carrier mode.

4. The detection system as claimed in claim 2 , wherein the determinator further comprises: a second sign judger, connected to the first carrier calculator, for outputting a second sign signal based on the first summation carrier signal; a third sign judger, connected to the second carrier calculator, for outputting a third sign signal based on the second summation carrier signal; and a selector, connected to the first to third judgers, for selecting the third sign signal as a fourth sign signal for output when the first sign signal is the positive sign, and otherwise selecting the second sign signal as the fourth sign signal.

5. The detection system as claimed in claim 4 , wherein the determinator further comprises a carrier mode latch, connected to the selector and the first sign judger, for producing a mode lock indication signal and locking the carrier mode at the single-carrier mode when the first sign signal and the fourth sign signal are the positive sign and a frame number is over a first threshold.

6. The detection system as claimed in claim 5 , wherein the carrier mode latch produces the mode lock indication signal and locks the carrier mode at the multi-carrier mode when the first sign signal and the fourth sign signal are negative sign and the frame number is over the first threshold.

7. The detection system as claimed in claim 1 , wherein the first TPS decoder comprises: an input signal estimator, for receiving the M frequency domain input signals to produce M estimative input signals, where the M frequency domain input signals indicate TPS signals of a frame in wireless transmission; a Fast Hadamard Transform (FHT) device, connected to the input signal estimator, for performing a Fast Hadamard Transform (FHT) operation respectively on the M estimative input signals to produce M Hardamard transform signals; a masking device, connected to the FHT device, for performing a masking operation respectively on the M Hardamard transform signals to produce the M first mask signals; and a maximum absolute generator, connected to the masking device, for performing the absolute operation respectively on the M first mask signals and selecting the maximum result to produce the first absolute maximum mask signal.

8. The detection system as claimed in claim 7 , wherein the FHT device performing the FHT operation respectively on the M estimative input signals to correspondingly produce M Hardamard transform signals is based on an equation as follows: H ⋒ q , m = ∑ k ⁢ a k q ⁢ y ⋒ k , est m , where indicates the M estimative input signals, indicates the M Hardamard transform signals, and a k q indicates a codeword corresponding to the M frequency domain input signals, for q=1, . . . , 32.

10. The detection system as claimed in claim 9 , wherein the maximum absolute generator producing the first absolute maximum mask signal is based on an equation as follows: Z ⋒ m Ma ⁢ ⁢ x = Max A q ∈ W ⁢  Z ⋒ q , m  , where indicates the M first mask signals, W indicates a Walsh codeword set corresponding to the active Walsh codeword set, A q indicates a codeword of the Walsh codeword set, and {circumflex over (Z)} m Max indicates a maximum one among the M first mask signals

11. The detection system as claimed in claim 7 , wherein the input signal estimator comprises M subcarrier input signal estimators in which a k-th subcarrier input signal estimator includes: a phase rotation and evaluation device, which receives the k-th frequency domain input signal and performs a 45-degree inverse phase rotation on the k-th frequency domain input signal in order to take the real part to thereby produce a real number input signal; a first weighting device, connected to the first weighting device, for performing a weighting operation on the real number input signal based on a first weight factor to produce a first weight input signal; and an accumulator, connected to the first weighting device, for accumulating the first weight input signal respectively of a plurality of successive frames to produce the k-th estimative input signal, for 1≦k≦M.

12. The detection system as claimed in claim 1 , wherein the second TPS decoder comprises: an input signal estimator, for receiving the M time domain input signals to produce M estimative input signals, where the M time domain input signals indicate TPS signals of a frame in wireless transmission; a Fast Hadamard Transform (FHT) device, connected to the input signal estimator for performing a Fast Hadamard Transform (FHT) operation respectively on the M estimative input signals to correspondingly produce M Hardamard transform signals; a masking device, connected to the FHT device, for performing a masking operation respectively on the M Hardamard transform signals to produce the M second mask signals; and a maximum absolute generator, connected to the masking device, for performing the absolute operation respectively on the M second mask signals and selecting a maximum result to produce the second absolute maximum mask signal.

13. The detection system as claimed in claim 12 , wherein the FHT device performing the FHT operation respectively on the M estimative input signals to correspondingly produce M Hardamard transform signals is based on an equation as follows: H ⋒ q , m = ∑ k ⁢ a k q ⁢ y ⋒ k , est m , where indicates the M estimative input signals, indicates the M Hardamard transform signals, and a k q indicates a codeword corresponding to the M time domain input signals, for q=1, . . . , 32.

15. The detection system as claimed in claim 14 , wherein the maximum absolute generator producing the second absolute maximum mask signal is based on an equation as follows: Z ⋒ m Ma ⁢ ⁢ x = Max A q ∈ W ⁢  Z ⋒ q , m  , where indicates the M second mask signals, W indicates a Walsh codeword set corresponding to the active Walsh codeword set, A q indicates a codeword of the Walsh codeword set, and {circumflex over (Z)} m Max indicates a maximum one among the M second mask signals

16. The detection system as claimed in claim 12 , wherein the input signal estimator comprises M subcarrier input signal estimators in which a k-th subcarrier input signal estimator includes: a phase rotation and evaluation device, for receiving the k-th time domain input signal and performing a 45-degree inverse phase rotation on the k-th time domain input signal so as to take the real part to thereby produce a real number input signal; a first weighting device, connected to the first weighting device, for performing a weighting operation on the real number input signal based on a first weight factor to produce a first weight input signal; and an accumulator, connected to the first weighting device, for accumulating the first weight input signal respectively of a plurality of successive frames to produce the k-th estimative input signal, for 1≦k≦M.

17. The detection system as claimed in claim 16 , wherein when the TPS input signals are transmitted in frequency domain, the first absolute maximum mask signal output by the first TPS decoder is greater than the second absolute maximum mask signal output by the second TPS decoder, and when the TPS input signals are transmitted in frequency domain, the second absolute maximum mask signal output by the second TPS decoder is greater than the first absolute maximum mask signal output by the first TPS decoder.

18. The detection system as claimed in claim 1 , the detection is applied to a receiving system, the receiving system comprising: an antenna for receiving a radio signal; a radio frequency (RF) front end connected to the antenna for reducing the radio signal from a radio frequency down to a baseband to produce a baseband signal; an analog to digital converter (ADC) connected to the RF front end for performing an analog to digital conversion on the baseband signal to produce an in-phase part and a quadrature-phase part; a pre-synchronizer connected to the ADC for compensating ppm offset of the in-phase part and a quadrature-phase part; a matched filter connected to the pre-synchronizer for performing a filtering to filter outband noises and produce a filtering signal; a synchronizer connected to the matched filter for performing a system synchronization based on the filtering signal; a channel estimator connected to the matched filter for performing a channel measurement on a transmission channel to produce a channel measure signal; a frame body processor connected to the matched filter and the channel estimator for performing a frame body processing based on the channel measure signal produced by the channel estimator so as to eliminate interference introduced by a frame header and acquiring frame body for the followed FFT operation based on timing information provided by synchronizer; a 3780-dot Fast Fourier Transform (FFT) connected to the frame body processor for performing an FFT operation on an output of the frame body processor to produce an unequalized frequency domain input signal; a single tap equalizer connected to the 3780-dot FFT for performing equalization processing based on zero-forcing criteria on the unequalized frequency domain input signal to produce a frequency domain input signal; and a 3780-dot inverse FFT (IFFT) for performing an IFFT operation on the frequency domain input signal to produce a time domain input signal; wherein the detection system, connected to the 3780-dot IFFT and the single tap equalizer, for determining the multi-carrier mode or the single-carrier mode based on the time domain input signal or the frequency domain input signal.